A substrate typically provides physical support, signal routing and other functions to an electrical system mounted thereon. A substrate may comprise a motherboard carrying discrete electrical components, integrated circuits (ICs), and the like, or an IC package supporting an IC die. Conventional substrates often include several layers of conductive planes to carry electrical reference (e.g., Power and Ground) signals.
FIG. 1 is a cross-sectional side view of a prior art system. Substrate 1 includes conductive planes 21, 22 and 23 separated by dielectric layers 30, 31, 32 and 33. Conductive via 40 passes through each of dielectric planes 30, 31, 32 and 33 and through a non-conductive area (e.g., an antipad) of each of conductive planes 21, 22 and 23. Conductive trace 50 is connected to via 40 and is to carry electrical signals to and from conductive interface 60 of an electrical component (not shown). Conductive interface 60 may comprise a connector, a socket, a pin, a solder ball, etc.
Via 40 may provide mechanical support for mounting conductive interface 60 to substrate 1, as well as a means to connect conductive interface 60 to a conductive trace residing in another layer of substrate 1. However, a stub portion of via 40 may present an undesirable capacitive load into a signal path that includes trace 50, thereby deteriorating the performance thereof.